Optical Design Considerations for Thin Photonic Power Converters with Textured Back Reflector

Photonic power converters (PPC) convert narrow-band light into electricity via the photovoltaic effect. In this study, we discussed optical design considerations of thin InAlGaAs PPCs with integrated pyramidal nano-textured back reflectors (BRs) under 1310 nm illumination. Simulation results using the finite difference time domain method revealed that multiple combinations of design space parameters yield similar total absorptance at 1310 nm but with different absorptance spectra. A tolerance study performed using one optimized design showed that a 70 nm variation in device thickness shifted BR-induced resonances from constructive to destructive interference and a 50 nm variation of the height and base width of nano-pyramids dropped the absorptance by more than 25% (absolute). Among all simulated designs, those with overlapping resonances around the target wavelength that incorporated a thin-film antireflection coating were the least sensitive to variations in the illumination wavelength.